This study investigates the effect of the timing of a Pedestrian Forward Collision Warning (PFCW) on the reaction time of the driver and the acceptance rate.
Forty-eight participants participated in the driving simulator experiment which was divided into two parts: a reaction part where reaction time was tested (between-subjects design) and an acceptance part where the acceptance of the system was assessed (within-subjects design). Seven conditions were tested: distracted drivers (warning at 3.5 seconds, 2.5 seconds, 1.5 seconds, no warning, and false warning) and focused drivers (warning at 2.5 seconds, and false warning). The warning was both audible and visual.
The focused driver scenario with the 2.5 seconds warning signal showed a significant lower reaction time compared to the other scenarios. The acceptance of the different scenarios contained a usefulness scale and a satisfying scale similar to the one used by Van der Laan, Heino, & de Waard (1997). Early and mid-time warning signals showed a significant difference on both scales compared to the false warning and the late warning scenarios.
Based on these results, we conclude that the timing of the warning signal has an influence on the acceptance rate. Conclusions regarding the reaction time need more data to be conclusive.